Inappropriate responses of the immune system may cause stressful symptoms to the involved organism. Exaggerated immune answers to foreign substances or physical states which usually do not have a significant effect on the health of an animal or human may lead to allergies with symptoms ranging from mild reactions, such as skin irritations to life-threatening situations such as an anaphylactic shock or various types of vasculitis. Immune answers to endogenous antigens may cause autoimmune disorders such as systemic lupus erythematosus, idiopathic autoimmune hemolytic anemia, pernicious anemia, type 1 diabetes mellitus, blistering skin diseases and different kinds of arthritis.
Immune responses occur in a coordinated manner, involving several cells and requiring communication by signaling molecules such as cytokines between the cells involved. This communication may be influenced or inhibited by, e.g., interception of the signals or block of the respective receptors.
Cytokines are secreted soluble proteins, peptides and glycoproteins acting as humoral regulators at nano- to picomolar concentrations behaving like classical hormones in that they act at a systemic level and which, either under normal or pathological conditions, modulate the functional activities of individual cells and tissues. Cytokines differ from hormones in that they are not produced by specialized cells organized in specialized glands, i.e. there is not a single organ or cellular source for these mediators as they are expressed by virtually all cells involved in innate and adaptive immunity such as epithelial cells, macrophages, dendritic cells (DC), natural killer (NK) cells and especially by T cells, prominent among which are T helper (Th) lymphocytes. At this time, Th1, Th2, Th17 and iTreg T-cell subclasses have been defined depending on the specific spectrum of cytokines expressed, and respective immunological responses modulated by them.
In this respect, principal cytokine products of Th1-cells are IFN-gamma, lymphotoxin-alpha and Interleukin 2 (IL-2). Th1-cells mediate immune responses against intracellular pathogens and are responsible for some autoimmune diseases (Mosmann et al., Annu. Rev. Immunol. 7 (1989), 145-173; Paul and Seder, Cell 76 (1994), 241-251). Th2-cells produce primarily IL-4, IL-5, IL-9, IL-10, IL-13, IL-25 and amphiregulin. Th2-cells mediate immune responses against extracellular parasites, and are involved in autoimmunity and allergies such as asthma, Type 1 diabetes mellitus, Multiple sclerosis (MS) and Rheumatoid arthritis (RA); see, e.g., Mosmann et al. (1989) and Paul and Seder, (1994), supra.
Some lymphocytes, such as subsets of gamma delta T cells and Natural Killer T (NKT) cells produce both Th1 and Th2 cytokines. Principal products of induced regulatory (iTreg) cells are IL-10, IL-35 and TGF-beta. The iTreg cells are involved in immune tolerance, lymphocyte homeostasis and regulation of immune responses.
Principal cytokine products of Th17-cells are IL-17 and IL-22; Th17-cells mediate immune responses against extracellular bacteria and funghi and are also involved in the mediation of inflammation and in autoimmune diseases such as psoriasis (Zhu and Paul, Blood 112 (2008), 1557-1569; Shevach, Immunity 25 (2006), 195-201). This spectrum of cytokine production pathophysiological activities is closely paralleled by subsets of gamma delta T cells.
Depending on their respective functions, cytokines may be classified into three functional categories: regulating innate immune responses, regulating adaptive immune responses and stimulating hematopoiesis. Due to their pleiotropic activities within said three categories, e.g., concerning cell activation, proliferation, differentiation, recruitment, or other physiological responses, e.g., secretion of proteins characteristic for inflammation by target cells, disturbances of the cell signaling mediated by aberrantly regulated cytokine production have been found as a cause of many disorders associated with defective immune response, for example, inflammation and cancer. Central in inflammation and autoimmune diseases are cytokines IL-17A and IL-17F, IL-22, IL-12, IL-23 and subtypes of the IFN-alpha and IFN-omega. Except IL-12, IL-23 and IFNs, said cytokines are expressed by the effector T-cell subset Th17 which have well-described roles in several autoimmune and allergic disorders and in tumour immunology.
Unregulated Th17 responses are associated with chronic inflammation and severe immunopathologic conditions. Studies on animal models and tissues of affected patients have confirmed the involvement of the Th17 pathway in chronic inflammatory diseases such as Acne vulgaris; Arthritis such as Gouty arthritis, Systemic lupus erythematosus (SLE), Osteoarthritis, Psoriatic arthritis, Rheumatoid arthritis (RA); Asthma; Celiac disease; Crohn's disease (CD); Chronic prostatitis; Dermatitis (e.g., atopic dermatitis); Diabetes mellitus Type 1; Glomerulonephritis; Hypersensitivities; Myocarditis; Multiple sclerosis; Inflammatory bowel diseases; Pelvic inflammatory disease; Polymyositis; Psoriasis (PS); Sarcoidosis; Vasculitis; Interstitial cystitis or in inflammation occurring due to reperfusion injury or transplant rejection. IL-17A induces the production of proinflammatory cytokines, chemokines, and matrix metalloproteins. This provokes inflammatory cell infiltration and destruction of extracellular matrix. In addition to IL-17A, the related cytokine IL-17F, that can heterodimerize with IL-17A, has recently been implicated in the pathogenesis of RA and CD.
IL-22, a third Th-17 related cytokine (Zenewicz and Flavell, Eur. J. Immunol. 38 (2008), 3265-3268) is a cytokine that acts mainly on epithelial cells. In the skin, it mediates keratinocyte proliferation and epidermal hyperplasia and plays a central role in inflammatory diseases, such as psoriasis. IL-22 is a signature product of Th117 cells, also secreted at functionally significant levels by other immune cells, especially NKp44/NKp46-expressing natural killer (NK) cells and lymphoid tissue inducer cells after IL-23 stimulation. Interleukin-22 (IL-22) is a member of the IL-10 family of anti-inflammatory cytokines that mediates epithelial immunity. IL-22 expression is enhanced in inflamed colon mucosa in individuals with inflammatory bowel disease. Importantly, IL-22 does not serve the communication between immune cells. It mainly acts on epithelial cells and e.g. hepatocytes, where it favors the antimicrobial defense, regeneration, and protection against damage and induces acute phase reactants and some chemokines (Wolk et al., Semin. Imunopathol. 32 (2010), 17-31).
IL-23 is a key cytokine in promotion of chronic inflammation, secreted by activated inflammatory cells like macrophages and dendritic cells (see for review Langrish et al., Immunological Reviews 202 (2004), 96-105; Ferraccioli and Zizzo, Discov. Med. 60 (2011), 413-24; further Langrish et al., J. Exp. Med. 201 (2005), 233-40; Vaknin-Dembinsky et al., J. Neuroimmunol. 195 (2008), 140-145; Melis et al., Ann. Rheumn Dis. 69 (2010), 618-23). Initially, IL-23 was found to have a role in supporting the expansion and maintenance of Th17 cells (Aggarwal et al., J. Biol. Chem. 278 (2003), 1910-1914; Weaver et al., Annu. Rev. Immunol. 25 (2007), 821-852). However, it was shown as having multiple effects on the immune response, including restraining the activity (intestinal accumulation) of Foxp3-positive regulatory T-cells (Barnes and Powrie, Immunity 31 (2009), 401-411; Izcue et al., Immunity 28 (2008), 559-570; Ahern. Immunity 33 (2010), 279-88) and inducing the expression of Th17-type cytokines from non-T-cell sources (Buonocore et al., Nature 464 (2010), 1371-1375; Morrison et al., Immunology 133 (2011), 397-408). It contributes to inflammation, e.g., in psoriasis and inflammatory bowel diseases (see publications supra and Duvallet et al., Ann. Med. 43 (2011), 503-511). IL-23 is composed of two subunits, p19 and p40; the latter subunit is shared with IL-12.
IL-17A, IL-22, oncostatin M, TNF-alpha, and IL-1alpha are potent cytokines produced by skin infiltrating immune cells and/or keratinocytes and they induce cutaneous inflammation (Boniface et al., J. Immunol. 178 (2007), 4615-4622; Nograles et al., Br. J. Dermatol. 159 (2008), 1092-1102; Guilloteau et al., J. Immunol. 184 (2010), 5263-5270).
Recent therapeutic approaches for chronic inflammatory diseases such as severe RA and PS involve blockage of tumor necrosis factor-α (TNF-α). While this method is highly effective in some cases, many patients are ‘non-responders.’ Furthermore, a sustained neutralization of TNF-α can enhance susceptibility to microbial infections, highlighting the need for alternative and more specific therapeutic approaches. So far, modulation of Th-17 cell function and/or differentiation has been most successful with monoclonal antibodies to IL-12 p40, which target both IL-12 (a heterodimer of p35 and p40) and IL-23 (a heterodimer of p19 and p40, a growth factor for Th17 cells). Such antibodies, ustekinumab and ABT-874 that target IL-12 p40, have been successful in moderate to severe chronic plaque psoriasis and CD (Miossec et al., N. Engl. J. Med. 361 (2009), 888-898, Steinman, Nat. Immunol. 11 (2010), 41-44).
The most feasible way to control the biologic effects of Th17 cells and cells with related properties, e.g., IL-17-producing gamma delta T cells, would be to target them and a selection of the effector cytokines they produce. This novel approach would enable a blockade of IL-22 in PS, and of IL-17A (and IL-17F) in RA and CD, leaving the other non-pathogenic arms intact for fighting pathogens and, in the case of IL-22, for exerting its tissue reparative and antimicrobial functions. Also, in some initial responders, the efficacy of the anti-TNF therapy drug wanes over time. Thus, severe cases not responding to monotherapy might require combination therapy with two or more biological drugs. Monoclonal antibodies against IL-17A have been developed for clinical application. Phase 2 trials of a monoclonal antibody against IL-17A (AIN457) for PS, CD and psoriatic arthritis are under way. So far, inhibitors of IL-22 have been tested only in pre-clinical models of autoimmune diseases (Miossec et al., N. Engl. J. Med. 361 (2009), 888-898, Steinman, Nat. Immunol. 11 (2010), 41-44).
Due to immunological responses to foreign antibodies, as mouse antibodies in humans (HAMA-response; Schroff et al., Cancer Res. 45 (1985), 879-885; Shawler et al., J. Immunol. 135 (1985), 1530-1535), mostly humanized versions of antibodies are used in present therapeutic approaches (Chan et Carter, Nature Reviews Immunology 10 (2010), 301-316; Nelson et al., Nature Reviews Drug Discovery 9 (2010), 767-774). One approach to gain such antibodies was to transplant the complementarity determining regions (CDR) into a completely human framework, a process known as antibody humanization (Jones et al., Nature 321 (1986), 522-525). This approach is often complicated by the fact that mouse CDR do not easily transfer to a human variable domain framework, resulting in lower affinity of the humanized antibody over their parental murine antibody. Therefore, additional and elaborate mutagenesis experiments are often required, to increase the affinity of the so engineered antibodies. Another approach for achieving humanized antibodies is to immunize mice which have had their innate antibody genes replaced with human antibody genes and to isolate the antibodies produced by these animals. However, this method still requires immunization with an antigen, which is not possible with all antigens because of the toxicity of some of them. Furthermore, this method is limited to the production of transgenic mice of a specific strain.
Another method is to use libraries of human antibodies, such as phage display, as described, for example, for the generation of IL-13 specific antibodies in international application WO 2005/007699. Here, bacteriophages are engineered to display human scFv/Fab fragments on their surface by inserting a human antibody gene into the phage population. Unfortunately, there is a number of disadvantages of this method as well, including size limitation of the protein sequence for polyvalent display, the requirement of secretion of the proteins, i.e. antibody scFv/Fab fragments, from bacteria, the size limits of the library, limited number of possible antibodies produced and tested, a reduced proportion of antibodies with somatic hypermutations produced by natural immunisation and that all phage-encoded proteins are fusion proteins, which may limit the activity or accessibility for the binding of some proteins. Similarly, European patent application EP 0 616 640 A1 describes the production of auto-antibodies from antibody segment repertoires displayed on phage. Phage libraries are generated from unimmunized humans in this respect (see, e.g., Example 1; page 16, lines 43-51; Example 2, at page 17, paragraph [0158], lines 57-58). However, also the methods described in this patent application suffer from above mentioned general disadvantages of antibodies generated from phage libraries, in comparison to antibodies produced and matured in a mammalian, i.e. human body.
In view of the above, there is still a need for additional and new compounds like binding molecules of high specificity which are tolerable in humans either for monotherapy or combinatorial approaches.
The solution to this problem is provided by the embodiments of the present invention as characterized in the claims and disclosed in the description and illustrated in the Examples further below.